When deleting, check the page history first to see if you can revert to an older version instead of deleting the entire page.

You can consider turning problematic pages into relevant redirects as an alternative to deletion.

Ideally, when an admin deletes a test page or other page with no useful content, it is a good idea to put a note on the author's talk page explaining things, and preserving the deleted content, pointing them to the sandbox in cases of tests.